—n. 1. something that provides mirth or amusement: A picnic would be fun. 2. enjoyment or playfulness: She's full of fun. 3. for or in fun, as a joke; not seriously; playfully: His insults were only in fun. 4. like fun,Informal.certainly not; of doubtful truth: He told us that he finished the exam in an hour. Like fun he did! 5. make fun of, to make the object of ridicule; deride: The youngsters made fun of their teacher.
—v.i., v.t. Informal.joke; kid.
—adj. 1. Informal.of or pertaining to fun, esp. to social fun: a fun thing to do; really a fun person. 2. Informal.whimsical: flamboyant: The fashions this year are definitely on the fun side.